1. Field of the Invention
The present invention relates to a light-emitting device used for a display and the like, and more particularly to a light-emitting device utilizing a light guide plate.
2. Description of the Related Art
In recent years, in a light guide plate utilized in a light-emitting device such as an advertising light panel and the like, a rear surface of the light guide plate is concavely processed by using a laser processing, mechanical processing or the like to make a particular design, and by forming a dot-shaped reflective portion, incident light from an end surface of the light guide plate is reflection-scattered on the reflective portion to light-emit the design (see for example, PCT International Publication No. WO2007-123202).
The description in Published Japanese Translation No. H3-503094 of the PCT International Publication states that incident light from an end surface is diffracted by a diffraction grating formed on a light guide plate, and an observer visually recognizes the diffracted light.
Incident white light is dispersed on a diffraction grating, and then diffracted to different angles depending on each wavelength, and therefore, when a certain design is composed with diffraction gratings and irradiated with light from the outside, the design shines in an iridescent color, or a color is changed with a change of viewing position. Given such visual effects, diffraction gratings have been widely used for decorating purposes.
However, in the method described in PCT International Publication No. WO2007-123202, a light-emitting color of a design is basically the same as a color of incident light, because the method utilizes reflection scattering of incident light that has entered onto a light guide plate. Therefore, although a color of incident light can be changed depending on positions and times, a light-emitting color within a defined area will basically be the same as a color of incident light.
In a light-emitting device described in Published Japanese Translation No. H3-503094 of the PCT International Publication, the whole design is made as a diffraction grating. In this method, a visual effect relating to a color specific to the diffraction grating can be obtained; however, when newly creating a design containing such a large sized diffraction grating, a large cost and a long time are required because a diffraction grating requires a fine pattern of a submicron level.
The present invention has been completed in light of the above, and an object of the present invention is to simply provide a light-emitting device that can add a visual effect with various colors to a design even if the light-emitting status of a light source is constant on a light guide plate that reflects light from a light source to a reflective surface formed on the light guide plate.